fix: tighten pairing endpoint validation

apps/windows_agent/src/TermRemoteCtl.Agent/Api/PairingEndpoints.cs

@@ -19,26 +19,35 @@ public static class PairingEndpoints
         {
             var code = pairingService.CreateCode(PairingCodeTtl);
             await auditLog.AppendAsync(
-                new AuditRecord("pairing_code_created", clock.UtcNow, code.Value, $"expires_at={code.ExpiresAtUtc:O}"),
+                new AuditRecord("pairing_code_created", clock.UtcNow, "pairing", $"expires_at={code.ExpiresAtUtc:O}"),
                 cancellationToken);
 
             return Results.Ok(code);
         });
 
         group.MapPost("/redeem", async (
-            [FromBody] RedeemPairingRequest request,
+            [FromBody] RedeemPairingRequest? request,
             PairingService pairingService,
             AuditLog auditLog,
             IClock clock,
             CancellationToken cancellationToken) =>
         {
-            var result = pairingService.Redeem(request.Code, request.DeviceName);
-            var response = new RedeemPairingResponse(result.Success, result.ErrorCode);
+            var validationError = ValidateRedeemRequest(request);
+            if (validationError is not null)
+            {
+                return Results.BadRequest(validationError);
+            }
+
+            var validatedRequest = request!;
+            var result = pairingService.Redeem(validatedRequest.Code!, validatedRequest.DeviceName!);
+            var response = result.Success
+                ? new RedeemPairingResponse(true, string.Empty, "accepted")
+                : new RedeemPairingResponse(false, result.ErrorCode, "rejected");
             var eventType = result.Success ? "pairing_redeemed" : "pairing_redeem_failed";
-            var details = result.Success ? request.DeviceName : result.ErrorCode;
+            var details = result.Success ? "accepted" : result.ErrorCode;
 
             await auditLog.AppendAsync(
-                new AuditRecord(eventType, clock.UtcNow, request.DeviceName, details),
+                new AuditRecord(eventType, clock.UtcNow, validatedRequest.DeviceName!, details),
                 cancellationToken);
 
             return result.Success ? Results.Ok(response) : Results.BadRequest(response);
@@ -46,8 +55,23 @@ public static class PairingEndpoints
 
         return endpoints;
     }
+
+    private static RedeemPairingResponse? ValidateRedeemRequest(RedeemPairingRequest? request)
+    {
+        if (request is null)
+        {
+            return new RedeemPairingResponse(false, "invalid_request", "rejected");
+        }
+
+        if (string.IsNullOrWhiteSpace(request.Code) || string.IsNullOrWhiteSpace(request.DeviceName))
+        {
+            return new RedeemPairingResponse(false, "invalid_request", "rejected");
+        }
+
+        return null;
+    }
 }
 
-public sealed record RedeemPairingRequest(string Code, string DeviceName);
+public sealed record RedeemPairingRequest(string? Code, string? DeviceName);
 
-public sealed record RedeemPairingResponse(bool Success, string ErrorCode);
+public sealed record RedeemPairingResponse(bool Success, string ErrorCode, string Status);

apps/windows_agent/src/TermRemoteCtl.Agent/Program.cs

@@ -25,3 +25,5 @@ app.MapGet("/health", () => Results.Json(new { status = "ok" }));
 app.MapPairingEndpoints();
 
 app.Run();
+
+public partial class Program;

apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Api/PairingEndpointsTests.cs

@@ -0,0 +1,112 @@
+using System.Net;
+using System.Net.Http.Json;
+using System.Text;
+using System.Text.Json;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using TermRemoteCtl.Agent.Configuration;
+
+namespace TermRemoteCtl.Agent.IntegrationTests.Api;
+
+public sealed class PairingEndpointsTests
+{
+    [Fact]
+    public async Task Redeem_Returns_BadRequest_When_Request_Is_Incomplete()
+    {
+        await using var fixture = new PairingApiFixture();
+        using var client = fixture.CreateClient();
+
+        using var response = await client.PostAsJsonAsync(
+            "/api/pairing/redeem",
+            new
+            {
+                code = "123456"
+            });
+
+        var payload = await response.Content.ReadFromJsonAsync<RedeemResponse>();
+
+        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
+        Assert.NotNull(payload);
+        Assert.False(payload.Success);
+        Assert.Equal("invalid_request", payload.ErrorCode);
+        Assert.Equal("rejected", payload.Status);
+    }
+
+    [Fact]
+    public async Task Redeem_Returns_BadRequest_When_Json_Is_Malformed()
+    {
+        await using var fixture = new PairingApiFixture();
+        using var client = fixture.CreateClient();
+        using var content = new StringContent("{\"code\":", Encoding.UTF8, "application/json");
+
+        using var response = await client.PostAsync("/api/pairing/redeem", content);
+
+        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task CreateCode_Does_Not_Write_Secret_Code_To_Audit_Log()
+    {
+        await using var fixture = new PairingApiFixture();
+        using var client = fixture.CreateClient();
+
+        var code = await client.PostFromJsonAsync<PairingCodeResponse>("/api/pairing/code");
+        var auditLog = await File.ReadAllTextAsync(fixture.GetAuditLogPath(), Encoding.UTF8);
+
+        Assert.NotNull(code);
+        Assert.DoesNotContain(code!.Value, auditLog, StringComparison.Ordinal);
+    }
+
+    private sealed class PairingApiFixture : WebApplicationFactory<Program>
+    {
+        private readonly string _dataRoot = Path.Combine(Path.GetTempPath(), "TermRemoteCtl.Tests", Guid.NewGuid().ToString("N"));
+
+        protected override void ConfigureWebHost(IWebHostBuilder builder)
+        {
+            builder.UseEnvironment("Development");
+            builder.ConfigureAppConfiguration((_, configBuilder) =>
+            {
+                configBuilder.AddInMemoryCollection(new Dictionary<string, string?>
+                {
+                    ["Agent:DataRoot"] = _dataRoot,
+                    ["Agent:BindAddress"] = "127.0.0.1",
+                    ["Agent:HttpsPort"] = "9443",
+                    ["Agent:WebSocketFrameFlushMilliseconds"] = "33",
+                    ["Agent:RingBufferLineLimit"] = "4000"
+                });
+            });
+        }
+
+        public string GetAuditLogPath()
+        {
+            var options = Services.GetRequiredService<IOptions<AgentOptions>>().Value;
+            return Path.Combine(options.DataRoot, "audit.log.jsonl");
+        }
+
+        public new async ValueTask DisposeAsync()
+        {
+            await base.DisposeAsync();
+            if (Directory.Exists(_dataRoot))
+            {
+                Directory.Delete(_dataRoot, true);
+            }
+        }
+    }
+
+    private sealed record RedeemResponse(bool Success, string ErrorCode, string Status);
+
+    private sealed record PairingCodeResponse(string Value, DateTimeOffset ExpiresAtUtc);
+}
+
+internal static class HttpClientJsonExtensions
+{
+    public static async Task<T?> PostFromJsonAsync<T>(this HttpClient client, string requestUri)
+    {
+        using var response = await client.PostAsync(requestUri, JsonContent.Create(new { }));
+        response.EnsureSuccessStatusCode();
+        return await response.Content.ReadFromJsonAsync<T>();
+    }
+}

apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/TermRemoteCtl.Agent.IntegrationTests.csproj

@@ -11,6 +11,7 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.8" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="xunit" Version="2.5.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" />
@@ -20,4 +21,8 @@
     <Using Include="Xunit" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\\..\\src\\TermRemoteCtl.Agent\\TermRemoteCtl.Agent.csproj" />
+  </ItemGroup>
+
 </Project>